Printing and coating method

ABSTRACT

A METHOD FOR COATING WEB AND OBJECT SURFACES WHEREIN A FORMULATION INCLUDING A COATING COMPONENT DISPERSED IN A SOLVENT VEHICLE IS DEPOSITED ONTO THE WEB OR OBJECT SURFACE WHICH IS THEN SUBJECTED TO ULTRASONIC IRRADIATION FOR FACILIATING VAPORIZATION OF THE SOLVENT CONSTITUENT IN THE FORMULATION AND/OR POLYMERIZATION AND CROSSLINKING   WITHIN THE COATING COMPONENT WHILE ON THE WEB OR OBJECT SURFACE.

' June 13, 1972 R. K. REMER 3,669,720

PRINTING AND COATING METHOD Original Filed May 14, 1965 3 Sheets-Sheet lJune 13, 1972 R. K. REMER 3,669,720

PRINTING AND COATING METHOD Original Filed May 14, 1965 3 Sheets-Sheet 2VIII/III [unanim- Eoberzff 562726;

M, KM,W aw z June 13, 1972 R. K. REMER 3,669,720

PRINTING AND COATING METHOD Original Filed May 14, 1965 3 Sheets-Sheet 5[2067225 jfoberf 7i 7297725/7 M, KM, 727

United States Patent 3,669,720 PRINTING AND COATING METHOD Robert K.Remer, Evanston, Ill., assignor to Inca Inks, Inc., Northbrook, 111.Original application May, 14, 1965, Ser. No. 455,936. Divided and thisapplication June 25, 1969, Ser. No.

Int. Cl. B44d U4 US. Cl. 11793.31 5 Claims ABSTRACT OF THE DISCLOSURE Amethod for coating web and object surfaces wherein a formulationincluding a coating component dispersed in a solvent vehicle isdeposited onto the web or object surface which is then subjected toultrasonic irradiation for facilitating vaporization of the solventconstituent in the formulation and/ or polymerization and crosslinkingwithin the coating component while on the Web or object surface.

BACKGROUND AND DESCRIPTION OF INVENTION This application is a divisionof Ser. No. 455,936, filed May 14, 1965, now abandoned.

The present invention relates to printing and coating methods andapparatus. More particularly, this invention is concerned withimprovements and innovations in methods of and apparatus forcontinuously printing or coating in a non-flammable atmosphere atravelling web or object surface by depositing thereon a suitable ink orcoating composition dispersed or dissolved in a heavy solvent vehiclefollowed by in-line treatment of the web or object surface with meansfor effecting improved solvent release and/or bonding of the ink orcoating composition to the substrate surface of the web or objectsurface.

By the method and apparatus of the present invention, it is possible toaccomplish high speed coating and printing of paper, plastic films,metal foils, textile fabrics, netting, non-Woven fabrics, Wires,filaments, fibers and threads. In addition, the method and apparatus ofthe present invention can also be used for coating of objects such asbottles, cans and the like. The ink or coating composition carried bythe heavy solvent vehicle can be deposited onto the substrate surface byany number of conventional techniques which include rotogravure, offsetgravure, reverse roll coating, air knife, dip coating, kiss roll,floating knife coating and the like. It has also been discovered thatpressurized spraying of liquid in the form of droplets or foam coatingscan be advantageously employed in particular coatingoperations.

According to the present invention the various printing and coatingprocesses referred to above are cooperatively combined with certainexpedited solvent release and/or ink and coating composition bonding orpolymerizing techniques. While the various embodiments of the inventionwill be more fully described below, they generally consist of subjectingthe printed or coated web to ultrasonic wave transmission, coronadischarge, and/or ultraviolet photopolymerization. As used in thisapplication, the term corona discharge is intended to include theprocess of treating a web or object surface with a high voltageelectrical discharge which promotes the advantageous cross-linking,polymerization and/or improved bonding of printing and coating depositson the web or object surface.

A significant aspect of the method and apparatus of the presentinvention is that it permits high speed, low temperature printing andcoating of Web and substrate surfaces. Besides offering importantadvantages by reason ice of its high speed coating and printing, themethod and apparatus of the present invention are particularlyattractive commercially since they enable substantially completerecovery of the heavy solvent. These heavy solvents include variouschlorinated and fluorinated solvents which will be more fully describedbelow.

It is, therefore, an important object of the present invention toprovide an improved method of and apparatus for continuously printing orcoating a web or object surface by first depositing thereon a suitableink or coating composition dispersed or dissolved as a monomer orpolymer in a heavy solvent followed by immediately subjecting the thusdeposited web to means for substantially improving the releasecharacteristics of the solvent and/ or the bonding or polymerization ofthe ink or coating deposit. 1

Another object of the present invention is to provide low temperatureprinting and coating of a web or object surface by first depositingthereon a suitable ink or coating composition dissolved as a monomer orpolymer in a heavy solvent vehicle followed by immediately subjectingthe thus deposited web to means for substantially improving the releasecharacteristics of the solvent and/or bonding or polymerization of theink or coating deposit.

Another object of the present invention is to provide a method andapparatus for continuously printing or coating a web or object surfacein a non-flammable atmosphere.

Another object of the present invention is to provide an improved Webcoating apparatus equipped with a unique solvent recovery hood adaptedto enable substantially complete solvent recovery in high speed printingand coating operations.

Another object of the present invention is to provide an improved methodof and apparatus for continuously coating a fast travelling web by thepressurized spraying of a coating material dispersed or dissolved in aheavy solvent onto the web.

Another object of the present invention is to provide an improved methodof and apparatus for printing or coating a web or object surface bydepositing thereon a suitable ink or coating composition dispersed ordissolved in a heavy solvent followed by immediately subjecting the webto ultrasonic sound Waves to substantially improve the releasecharacteristics of the solvent for facilitating evaporation thereof.

Another object of the present invention is to provide a method of andapparatus for printing or coating a web or object surface by depositingthereon a suitable ink or coating composition which includes apolymerizable component and then subjecting the web to polymerizationpromotion means' for effecting cross-linking Within the deposited ink orcoating to change the characteristics of the coating.

Another object of the present invention is to provide a method of andapparatus for converting a web or object surface coating havinghydrophillic characteristics to an oleophillic coating throughultraviolet treatment of said coating.

Another object of the present invention is to provide an improved methodof and apparatus for coating a web or object surface by first applying acoating material containing a polymerizable component onto the web orobject surface followed by in-line treatment of said coated web orobject surface with polymerization means for directly converting thevapor product absorbed on the web into a plastic coating.

Another object of the present invention is to provide an improved methodof and apparatus for printing or coating of a Web or object surface bydepositing thereon a suitable ink or coating material containing aphotopolymerizable component and immediately subjecting the web orobject surface to in-line treatment with radiation means for promotingpolymerization within the deposited ink or coating material.

Another object of the present invention is to provide an improved methodof and apparatus for printing or coating a web or object surface bydepositing a suitable ink or coating composition carried by a heavysolvent vehicle and then immediately subjecting the thus deposited webor object surface to corona discharge treatment for promoting bonding ofthe deposited material to the web or object surface and/or changing thephysical or chemical characteristics of the coating.

Another object of the present invention is to provide an improved methodof and apparatus for printing or coating a web or object surface withink or coating compositions which include a photopolymerizableconstituent by first depositing the ink or coating composition on theweb or object surface and then immediately subjecting the depositedcoating is ultraviolet rays for promoting cross-linking within thecoating and bonding thereof to the web or object surface.

Another object of the present invention is to provide an improved methodof and apparatus for high speed coating of a web by depositing thereonat low temperatures a coating composition containing an iron oxide component dispersed in a fluorinated or chlorinated solvent and thensubjecting the thus deposited web to a magnetic field prior toevaporation of the solvent so that predetermined particle alignment canbe easily obtained thereby.

Another object of the present invention is to provide an improvedapparatus for high speed printing or coating of a fast moving web byproviding ultrasonic sound transmitting means to effect uniformdistribution of the ink or coating composition in the solvent vehicle soas to enable uniform application of the ink or coating to the web.

Another object of the present invention is to provide a method of andapparatus for coating a web surface with an improved polymericcomposition by depositing on the web surface a coating compositiondispersed in a nonflammable heavy solvent vehicle and simultaneously atlow temperatures subjecting the thus deposited web to a magnetic fieldand corona discharge treatment.

Other and further objects of the present invention will be apparent fromthe following detailed description of the accompanying drawings wherein:

FIG. 1 is a schematic view illustrating one embodiment of the apparatusof the present invention wherein ultrasonic wave treatment is employedin combination with three-roll reverse coating of a moving web;

FIG. 2 is a fragmentary schematic view of the lower end fa condenserunit such as illustrated in FIG. 1 modified for aerosol or foam sprayingof the web;

FIG. 3 is a fragmentary schematic view such as shown in FIG. 2illustrating the lower end of the condenser unit of FIG. 1 which hasbeen modified for rotogravure printing or coating of the web;

FIG. 4 is a schematic view illustrating another embodiment of theinvention wherein corona discharge treatment is employed in combinationwith aerosol or foam spraying of a moving web;

FIG. 5 is a fragmentary schematic view of the lower end of a condenserunit of the type illustrated in FIG. 4 but modified for rotogravureprinting or coating of the web;

FIG. 6 is a schematic view illustrating a third embodiment of thepresent invention wherein ultraviolet photopolymerization means isemployed in combination with pressurized liquid or foam spraying of amoving web;

FIG. 7 is a schematic view of an apparatus embodying principles of thepresent invention which is particularly adapted for coating a moving webwith magnetic oxide particles and aligning these particles while on theweb prior to solvent removal therefrom; and

FIG. 8 is a schematic view of the lower end of a condenser unitembodying principles of the present invention 4 and modified for hotmetal drying of a printed or coated web substrate.

Referring to the drawings, and with particular reference to FIG. 1, thenumeral 20 generally designates a three roll reverse coating unitconstructed in accordance with one aspect of the present invention. Asis shown, coating unit 20 includes a lower shell 21, an intermediateshell portion 22 and a hood 23 which is equipped to collect and condensethe evaporated solvent.

The coating depositing component of unit 20 is of the three-roll reversedesign and includes an impression roller 24, an application roller 26and a reverse roller 27. Application roller 26 is positioned so that inrotating it picks up the coating formualtion to be deposited from opentank or fountain 28. A doctor blade or knife 29 is arranged to controlor meter the amount of coating formulation picked up by applicationroller 26. Reverse roller 27, having a wiping action on applicationroller 26, removes the excess coating formulation from applicationroller 26 and is adjustable for controlling the thickness of the coatingdeposit and also acts to insure that web 30 receives a smooth anduniform coating layer. Uniformity of the applied coating formulationpicked up by roller 26 is provided for by means of a high frequencyimpulse generator 31 positioned on the bottom of fountain 28. In thiscapacity, ultrasonic generators such as those commercially availablefrom The Bendix Company (Davenport, Iowa) and Multisonic Corporation(Westbury, N.Y.) can be advantageously employed. The high frequencygenerator unit 31 includes a transducer for converting the highfrequency electrical energy from the generator to ultrasonic waveswhich, in turn, subject the coating formulation in fountain 28 to highfrequency energy which acts to maintain complete and uniformdistribution of the coating material in the fiuorinated or chlorinatedsolvent vehicle.

A coil 32, fitted around the shell portion 21, provides temperaturecontrol means to the coating apparatus. For example, in low temperaturecoating operations such as are discussed below in reference to FIG. 7,coil 32 can be used to chill or cool the shell zone adjacent to wherethe web is coated. Similarly, where very heavy coatings are applied toweb 30 it may be desirable to send a heated fluid through coil 32 inorder to facilatate evaporation of the solvent vehicle. In this regard,it will of course be appreciated that coil 32 can be sized in accordancewith the particular cooling or heating requirements of the coatingoperation. To the same effect, rollers 24 and 26 may be electricallyheated in a well known manner by any of several commercially availableelectrical heater units in order to hasten evaporation of the solvent.

- Shell portion 22 is equipped with heating elements for effectingevaporation of the solvent vehicle which is absorbed by the travellingweb. These heaters will vary in accordance with the web material andcoating formulation employed. For example, when coating webs which havea porous texture, it is desirable to position the heating element 33 onthe back or uncoated surface of the web 30 so that the solvent vehicleis not driven through the web. On the other hand, when coating nonporouswebs, such as metal foils, the heating element 34 is advantageouslypositioned on the coated side of the travelling web 30. In someoperations it is desirable to simultaneously heat both sides of thetravelling web 30.

A condenser 36 on the return side of shell portion 22 acts to condensethe solvent vapors evolved from the fountain or bath 28 and web 30. Atthe lower end of condenser 36, a solvent collecting trough 37 picks upthe liquified solvent and returns it to a storage vessel (not shown)where it is mixed with make-up quantities of coating material andreturned to fountain 28 for reuse. Condenser 36 can be advantageouslyconstructed with a corrugated wall for providing'additional coolingsurface as is disclosed in my patent, No. 3,067,056, entitledImprovements in Printing with Ink Compositions Having Volatile Solvents.

In accordance with an important aspect of the present invention, hood 23is equipped with a central opening therein through which the evaporatedsolvent passes. Directly above opening 38 is a Y-shaped baflle 39 onwhich the vapors condense and run down onto an annular platform 40 forpassage through conduit 41 to the storage chamber referred to above inconnection with trough 37. Hood 23 and bafile 39 are preferably of ajacket construction with hood 23 being equipped with an inlet 42 andoutlet 43 in order to permit the passage of cold water through innerchamber 45 so as to facilitate solvent condensation. In order to improvesolvent recovery it is also desirable to communicate the interiorchamber 44 of hood 23 with a vacuum pump or other pressure reducingmeans.

As is shown in the embodiment illustrated in FIG. 1, web 30 enterscoating unit through an opening 46 and is directed around freelyrotatable guide rollers 47a and 4712 down and around impression roller24. In this connection, it has been found that urethane and Thiokol(polysulfide synthetic elastomers produced by Thiokol Corporation,Trenton, NJ.) rubber-like impression rollers can be made permanentlyself-lubricating by use of molybdenum disulfide and tungsten disulfide.A heating element 48 can, if desired, be employed to preheat the webprior to its contacting the impression roller 24 in order to improve andfacilitate the coating of certain web materials. For example, apreheating unit is desirably used in connection with silicon coating ofsteel and other metal webs and foils.

After receiving the coating deposit from application roller 26, web 30travels around guide roller 49 and is directed upwardly toward theintermediate shell section 22 where the transducer elements 50 and 51are located. Transducer elements 50 and 51 are preferably of sutficientsize so as to cover the entire width of the coated web. Each of thetransducers is connected to a generator (not illustrated) from whichthey receive high frequency electrical energy and convert it toultrasonic waves, generally in the range of from 20,000 to 25,000 cyclesper second. These high frequency waves produce pressure variations inthe solvent which cause minute bubbles to form and instantly collapse.As a result, solvent release or evaporation is thereby greatlyfacilitated. It should be noted that with some coating formulations, itis believed that the ultrasonic wave treatment also assists in thein-situ cross linking or polymerization of the coating formulation.

Another important advantage of the ultrasonic treatment, such asprovided by transducers 50 and 51, is that it enables more uniformcoating thickness. In this regard, a common problem in reverse rollercoating has been that there is a tendency for the coating materials tothin out at the middle of the" roller and build up along the outeredges. With ultrasonic treatment of coated webs as disclosed in thisapplication the unevenly applied coatings are smoothed out. In fact,coatings applied by a three roll reverse coating unit equipped forultrasonic wave treatment of the coated web favorably compare in qualityand uniformity to those applied by offset gravure techniques.

In the illustrated embodiment, two transducer elements are shown. Itshould be noted, however, that in many coating operations a singletransducer element may be used. Generally, positioning the transducerelement on the coated side of the web is the most desirable arrangement(such as transducer 51).

Solvent evaporation can be further aided by introducing warm airadjacent the transducer element such as through opening 52 in the unitbetween bottom portion 21 and intermediate section 22. Heated air from afurnace or other source can be used in this capacity.

It is intended that the principal heating of the web be done by heatingunits such as 33 or 54. These heating elements should be of sufficientsize and output so as to heat the solvent carried on the web substrateto its boiling point.

After being directed past transducer elements 50 and 51, the travelingweb is directed around rollers 53, 54, 55 and 56 to a wind-up roller(not illustrated). With the present invention wind-up is not necessarysince the travelling web leaves coating unit 20 in a substantially drycondition and can then be directed to a printing unit or, if desired,another coating unit so that multiple layered deposits can be applied toa web material in a continuous operation. In this. connection, with theapplication of multiple coatings to a web substrate, it is sometimesdesirable to direct the web 30 after it has re ceived the coatingdeposit from the impression rollers 24 to a second coating unit beforethe first coating deposit formulation has had the solvent evaporatedtherefrom. In such operations, multiple coatings can be applied to theweb substrate, all of which are dried at the final stage of the coatingoperation. This latter technique is particularly advantageous wherethere is to be either chemical or physical bondings between the variouscoating layers.

Since most of the conventionally available transducer elements areadversely effected by heat, it is desirable to locate these elementsaway from the heaters 33 and 34.

Examples of coating and printing formulations which may be used inaccordance with the method and apparatus of the present invention aredescribed in my copending application entitled Printing and Coating Compositions, Ser. No. 124,329, filed July 17, 1961 and in my previouslyreferred to patent, No. 3,067,056. Additional formulations of coatingand ink formulations are described below in the detailed examples whichare a part of this application.

In accordance with the present invention, each of these formulationsincludes a heavy solvent, particularly those of the chlorinated andfluorinated type, such as, for example, methyl chloroform, methylenechloride, trichloroxylene, perchloroethylene, pentachloroethylene,ethylene dichloride, trichloromethane, chlorodifluoroethane, and otherfluorinated and chlorinated solvents exhibiting like properties andcharacteristics. Similarly, various combinations and azeotropic mixturesof these fluorinated and chlorinated solvents may be advantageouslyused. A typical example of an azeotropic mixture which can be used asthe solvent component of a coating or printing formulation consists of43 percent perchloroeth'ylene and 57 percent 2-Nitropropane (percentageson a volume basis).

Solvents of the type described above olfer a number of importantadvantages when used with the method and apparatus of the presentinvention. For example, since the fluorinated and chlorinated solventsare dry solvents, they do not wet or hydrate surfaces to which they areapplied, even where the surfaces are highly porous or composed ofabsorptive materials.

Another important advantage is that the solvents have unusually highdissolving and suspending capacities particularly when used with ink orcoating formulations which include resinous material, fillers andpigments. In this regard, when using these solvents it is possible toprovide ink and coating compositions which contain up to as much as 5 0%to 60% solids as compared to conventional ink or coating compositionswherein the solid content does not exceed 25% by weight.

The flurinated, chlorinated and like solvents will also readily vaporizeat temperatures in the low to interme diate range. For example, manyfluorinated solvents will boil at temperatures lower than 32 F. whilemost chlorinated solvents boil at temperatures between 75 F. and F. Inthis connection, it has also been noted that when used with theapparatus and method of the present invention practically all of thesolvent can be recovered. This feature is particularly important sincethese solvents are relatively expensive and excessive loss thereof wouldprohibit their use in commercial printing and coating operations. Lowtemperature boiling offers the additional advantage of permittingdeposit of the coating or ink composhition to a web or object surface attemperatures which result in very low formulation penetration of theweb, thereby enabling unusually thin coatings to be uniformly applied.Coating at these low temperatures as embodied in the present inventionis believed to be novel. It is particularly important in a number ofcoating and printing operations, such as, for example, the iron oxidecoating of webs as described in connection with the apparatus shown inFIG. 7, wherein depositing of the resin-iron oxide coating dispersed ina chlorinated or fluorinated solvent, controlled particle alignment andsolvent removal are accomplished at unusually high speeds in a singlecoating unit.

The use of fluorinated and chlorinated solvents with the method andapparatus of the present invention offers another important advantage inthat these solvents provide a non-combustible, inert atmosphere. Thisproperty of the halogenated solvents is particularly advantageous sinceit permitsthe use of techniques such as corona discharge treatment ofcoated webs without requiring that the entire system be maintained undervacuum conditions. By the present invention, the advantageouspolymerization-inducing properties of corona discharge treatment areable to be used on coated webs in a non-vacuum environment to providein-situ polymerization of the deposited coating or ink, as well as otherproperty changing treatment thereof. For example, as is described in thepresent application, hydrophillic coatings can be changed tooleophilliccoatings by means of actinic light treatment without webdamage or danger of explosions or fire.

In FIG. 2, another variation of the embodiment illustrated in FIG. 1employing high frequency sound waves to effect and facilitate solventrelease is shown. In this variation, the coating is uniquely applied bymeans of an aerosol spray nozzle 60. Nozzle 60 is preferably positionedin section 21 of coating unit 20 with the transducer units 50 and 51positioned adjacent thereto.

The particular coating formulations which can be advantageously usedwith the aerosol spraying technique of the present invention are morefully described in the examples below, however, it should be noted thatvarious chlorinated and fluorinated hydrocarbons as well as nitrousoxide and carbon dioxide can be used as the propellant. Suitableadditive to the fluorinated and chlorinated solvents for use in aerosolspraying include the gl'ycols, glycol ethers, polyglycols, propylenecarbonate, dimethyl sulfoxide, formamide (acting both as a cosolvent andcoalescing agent) as well as alcohols, ketones, esters, hydrocarbonsolvents and plasticizers of the solvating yp I It is important to notethat the aerosol spraying technique of the present invention is notlimited to the spraying of liquids but also includes pressurized foamcoating (i.e. those coating formulations which include surfactants whichproduce minute bubbles and give the material a frothy mass). Foamcoating material is particularly desir able for use in coating metals,plastics and textiles.

While not specifically illustrated in FIG. 2, it should be realized thanintermediate shell section 22 and hood tom of the shell section 21. Thisliquid bath includes an ink or coating composition which is dispersed ordissolved in a fluorinated or chlorinated solvent. Particularformulations which can be advantageously employed are more completelydescribed below and, are also found in the above referred to Patent3,067,056 and copending application Ser. No. 124,329. When heating isdesired, the temperature of the bath may be controlled in any of anumber of Ways such as by passing a heating fluid (gas or liquid)through a coil 64 located in the bottom of the shell 21. Any fluidheating medium of suitable heat transfer and other physicalcharacteristics may be used, such as steam, oil or Dowtherm (eutecticmixture of phenyl ether and 26.5% of diphenyl oxide having a boilingpoint of 258 C.). While not shown, a coil 32 such as shown in FIGS. 1and 2 may also be provided.

Quartz or other semiconductor type transducers and 51 similar to thoseshown in FIGS. 1 and 2 are provided near the roto'gravure cylinders sothat the solvent molecule exciting effect produced thereby is initiatedbefore the solvent molecules are absorbed into the web material.Transducer placement is particularly critical when porous substrates arebeing printed or coated. The coating deposit or ink containing bath 65can be continuously fed through a conduit 66 which in turn is suppliedby trough 37, conduit 41 and a make-up coating or ink sup ply, toprovide a completely automatic coating or printing operation.

In FIG. 4, a coating apparatus 70- constructed in accordance withanother aspect of the present invention is illustrated. Except ashereinafter described, coating apparatus 70 is substantially the same asthe three-roll reverse coating apparatus 20 of FIG. 1. Accordingly, theuse of like reference numerals in FIG. 4 will denote that components sodesignated are identical to those described above. It is important tonote that the novel solvent recovery hood 23 described more fully inconnection with FIG. 1, can also be advantageously utilized in thepresent embodiment.

In accordance with the present invention, coating unit 70 is equippedfor corona discharge treatment of the coated web. As is schematicallyshown, the corona treatment components include a generator 71, connectedto an electrode 72 and a dielectric covered treater roll 73. Web 30passes around treater roll 73, receiving the deposit of coating materialdispersed in the fiuorinated or 23 are positioned over shell section 21as is shown in FIG. 1 to provide a coating unit 20 identical to thatshown in FIG. 1 with the exception of the aerosol coating nozzle 60.

-In FIG. 3, a third modification of the ultrasonic solvent releasecoating unit is illustrated. As is shown, this modification employs arotogravure printing or coating operation such as that which is morecompletely disclosed in my earlier Patent 3,067,057 referred to above.In this modification, web 30 passes around the impression roller 62 andreceives a printing or coating deposit from printing cylinder 63.Cylinder 63 may have an over-all printing surface or it may carry adesign whereon there are printing areas and non-printing areas. Thelower portion of cylinder 63 runs in a liquid bath contained in thehotchlorinated solvent from the nozzle 60 and is then immediatelysubjected to a high voltage electrical discharge from electrode 72.Treater roll 73- is generally spaced a minimum distance of at leastone-sixteenth inch 0A from electrode 72. The particular spacing betweentreater roll 73 and electrode 72 will, of course, vary in accordancewith the output of generator 71 and is best defined as being that whichbest accomplishes the desired treatment of the coated or printed web.Treater roll 73 is connected to a suitable ground 74.

Electrode 72' produces an electrostatic discharge which jumps the airgap resulting in the corona discharge. Generally, the electrode shouldbe sized so that it produces a corona discharge across the entire widthof the web being coated. Commercially available electrodes of the typewhich include the multiple glass-covered variety, multiple-vinyl oracrylic covered type, bare knife edge, or shoe-type electrodes can beadvantageously employed.

Generator 71 can usually consist of a tesla coil which is energized by aspark-gap oscillatory circuit. In this connection, it has been foundthat a voltage of from 19 to 36 kilovolts can be advantageously used toprovide a corona discharge which, depending upon the particular coatingmaterial being used, will produce the desired results.

It has been found that corona discharge treatment can be advantageouslyemployed to obtain in-situ polymerization of the coating deposit,improved bonding of the coating to the web by reason of a permanentcharge being placed on the deposited coating material, and bettersolvent release therefrom.

Polymerization or cross-linking of the deposited material generallyoccurs where the coating or ink deposit is comprised of a dielectricpolymer such as paraffin wax, asphaltic sulfurized fossil resins,carnuba wax, beeswax, nylon, acrylics, and saran. These ink or coatingdeposit materials are, in accordance with the present invention,dispersed or dissolved in a fluorinated or chlorinated solvent and, whenused in an aerosol application technique such as shown in FIG. 4,suitably combined with a satisfactory pressurizing medium. Thetemperature at which the coating or ink materials are deposited willvary in accordance with the intended coating operation. As was explainedpreviously, the present invention finds advantageous utility in that itcan be used for both low temperature coating (below 32 F.) or, ifdesired, high temperature coating (up to 180 F.) with substantiallycomplete solvent recovery in both cases.

It is important to realize that the solvent carrying the polymerizablecoating or ink deposit is not itself polymerized when subjected to thecorona discharge treatment from electrode 72. When the polymerization orcrosslinking of the coating or ink deposit takes place, there is notbelieved to be any chemical reaction involving the solvent. However, ithas been found that the release characteristics of the fluorinated orchlorinated solvent are thereby greatly increased. While the applicantdoes not wish to be bound to a particular theory explaining thisphenomenon, it is believed to result by reason of the newly formedpolymers having a reduced affinity for the solvent.

Coating and ink deposit compositions having a polycrystalline structureprovide another advantageous characteristic when subjected to coronadischarge treatment as embodied in the present invention. It has beenfound that improved bonding results by reason of a permanent chargebeing placed on the newly formed polymers, which charge acts to bond thepolymers to the web substrate. In addition to significantly improvedbonding, the polycrystalline deposits when subjected to the coronadischarge undergo a chemical transformation which provides unexpectedand desirable results. For example, a waxparaffin coating applied topaper when subjected to corona discharge takes on a very high gloss andexhibits physical properties as it becomes electrified very much likethat of an electrically charged surface. This permanent charge improvedbonding characteristic is not obtained with the hydrophilic polymerssuch as regenerated viscose and ethyl cellulose since these materialsare not of a polycrystalline structure.

As is illustrated in FIG. 5, corona discharge treatment can be used withrotogravure and other types of printing and coating apparatus. Generator71 and electrode 72 of FIG. are of the same design and construction astheir counterparts in FIG. 4. Dielectricially covered treater roll 73a,however, is shown in spaced-away relation from impression roller 62 inthis embodiment, illustrating that corona discharge treatment can beprovided at locations other than immediately adjacent to where thecoating or printing formulation is applied.

FIG. 6 illustrates another embodiment of the present invention. In thismodification ultraviolet polymerization is used for promotingcross-linking of the coating or ink deposit. As was true with coronadischarge treatment of polycrystalline coating and printingcompositions, improved bonding results with ultraviolet techniques viathe placing of a permanent charge on the newly formed polymers.

While aerosol spraying is illustrated as the coating depositing means,it will be appreciated that other coating and printing methods wellknown in the art may be employed such as rotogravure, reverse roll, etc.

Actinic radiant energy for producing photopolymerization of the coatingor ink deposit is provided from ultra violet lamps 76 mounted on a bar77 suitably supported at the opening 52 in the coating unit 78. Severalmakes of ultraviolet lamps are commercially available which can be usedfor this purpose including those often referred to as sun, Xenon,mercury vapor or quartz lamps. Other sources of radiant energy includecathode ray tubes, lasers, masers and sources of gamma and betaradiation. So-called solar furnaces may also be used where practical.

The solvents which may be employed in this technique are similar tothose previously described. They generally have a low boiling point,yield vapors that are heavier than air and are easy to condense. Theseicnlude methylene dichloride, perchloroethylene, trichloroethylene,Chlorotene NU (Dow), pentachloroethylene, ethylene dichloride,trichloromethane, dichloromethane, trichlorotrifluoroethane,trichloromonofluoroethane and hexane, and various mixtures thereof.Aqueous solvents and diphase systems may also be used.

Among the coating and ink materials which can be advantageously used inconnection with the photopolymerization technique described in thepresent embodiment, are the water soluble hydrophillic polymers such asgelatin, polyampholytes, polyvinyl acetate, polyvinyl alcohol,polyvinylpyrrolidone, isopropyl cellulose (Klusel, Hercules Powder Co.),methyl cellulose, collagen and other proteinatious matter. Thesematerials are soluble in the fluorinated and chlorinated solvent and canbe applied in very thin films to the substrate surfaces. When subjectedto ultraviolet light they become oleophillic coatings.

FIG. 7 illustrates an embodiment of the present invention havingparticular utility for high speed coating of a web with an ironoxide-resin composition. With the apparatus shown, it is possible toapply magnetic iron oxide particles on a substrate surface, align theseparticles in a predetermined and desired arrangement, and then providein-line treatment of the thus coated web to polymerize the resin andobtain substantially complete solvent recovery.

An important aspect in the coating of iron oxide particles is that thesolvent vehicle remains on the substrate surface until such time as thepredetermined and desired particle arrangement has been obtained.Accordingly, it is desirable that low temperature coating techniques beapplied. In this connection, coil 32 can generally be supplied with arefrigerant or cooling water so as to maintain the temperature in thelower shell portion 21 substantially below the boiling point of theparticular solvent employed.

The coating deposit formulation employed in this coating techniquegenerally includes the iron oxide particles, a polymer resin, and afluorinated or chlorinated solvent. Typical examples of the magneticiron oxides are those commercially available as IRN-351, IRN-1l0,IRN-llS and IRN-ZZO (C. K. Williams Co.). The preferred polymer resinsare those which are soluble in the fluorinated or chlorinated solventsuch as, for example, an acrylic ester copolymer identified commerciallyas Hycar 1432 (B. F. Goodrich). The fluorinated and chlorinated solventsinclude those mentioned above. In using coating formulations containingiron oxide particles, it is highly desirable to provide at the bottom offounation 28 a high frequency impulse generator 31 of the type describedin connection with FIG. 1.

After the coating deposits containing the magnetic iron oxide particles,polymer resin and solvent vehicle are applied to the substrate surfaceby the roller 63, the coated web 30 travels to a position where it isspaced adjacent to a magnetic field generating unit, schematicallyillustrated in FIG. 7 and designated by the reference numeral 80. Thesolvent and polymer resin are still intact on the web substrate becauseof the low temperatures maintained in this section of the coating unitthereby permitting movement of the particles in accordance with themagnetic influence imparted thereto by particle alignment component 80.The coated web passes from the region directly adja- 11 cent thealignment unit 80, to a location in the coating unit where the solventrelease means act to facilitate and evaporate the solvent vehicle. Ifdesired, the various polymer.- ization techniques described in thepresent application can be used to polymerize the resin component of thecoating formulation.

As is shown in FIGS. 1, 4, 6 and 7, heating elements 33 and 34 can beused to evaporate the solvent from the coated web or object surface. Anyconventional electric or infra-red heaters may be employed, the primaryrequirement being that it have a sufficient output so as to heat thesolvent component to its particular boiling point. Similarly, selectiveheating techniques, as provided by high frequency heating and dryingunits (such as marketed by the Radio Frequency Company of Medfield,Mass.) may be advantageously employed for unusually quiok and thoroughsolvent vaporization.

The hot metal dip drying technique of the present invention findsutility not only in drying webs to effect solvent removal, but also inremoving any electrical charges from webs composed of saran(polyvinylidene chloride), cellulose acetate and like materials.

As is illustrated in FIG. 8, web 30 after receiving a deposit of acoating formulation from aerosol nozzle 60 is directed around guiderollers 85, 86 and 87 into a molten metal bath 88. The temperature ofmetal bath 88 is maintained by heating elements (not illustrated) atleast as high as the boiling point of the particular solvent componentof the coating formulation. Similarly, the depth of bath 88 is sized topermit sufficient contact of the coated web with the molten metal foreffecting complete drying thereof. In this regard, the bath size willalso be directly proportional to the web speed. Typical examples ofmetals which can be utilized include bismuth, tin, Woods alloy and leadas well as other metals having melting points ranging from 80 F. to 2000F.

After entering molten metal bath 88 web 30 is directed around roller 89upwardly toward coil 93 which is supplied with cold water or arefrigerant for cooling the hot web. While the illustrated embodiment isof a coating operation, it will be appreciated that this rapid dryingtechnique may be utilized in printing operations also. Similarly, moltenmetal web and object dipping can be used as a pretreatment technique inmolding opera tions as well as in the forming of laminates.

Reference is now made to the following examples 6? a more detailedexplanation of the present invention.

EXAMPLE I A nylon polyamide coating can be applied to a web in thefollowing manner. The web is first padded or surface coated with aformulation prepared in accordance with the following relativequantities:

Parts by weight Sodium carbonate 40 Hexamethylenediamine 22 Water 500The above ingredients are thoroughly mixed and applied via conventionaldip coating methods. Following dip coating, the coated web is thendirected to a coating unit 20, such as disclosed in FIG. 1 of thisapplication. Fountain 28 of coating unit 20 contains a coatingformulation composed of the following ingredients:

These high frequency waves serve to activate the methylene chloridethereby facilitating solvent removal. Heaters 33 and 34 providesufficient output to heat the solvent vehicle contained within the websubstrate to 104 F. (the boiling point of methylene chloride). Thesolvent vapor is then collected and condensed in the solvent recoveryhood.

EXAMPLE II This example illustrates the application of a gelatin coatingto a paper substrate via a three-roll reverse coating technique. Thecoating formulation is first prepared by thoroughly mixing 3200 ml. ofwater with 800 grams of 225 bloom gelatin and allowing the mixture tostand about one hour at which time all the water is absorbed by thegelatin to produce a swollen mass. The gelatinous mass is then warmed tobetween 60 F. and 65 F. and again thoroughly mixed to insure ahomogeneous solution with water being added to bring the volume up 4000ml. To the above solution, 2000 ml. of methylene chloride are added in amixing apparatus equipped for cold water condensing to prevent solventloss. In this connection, it has been found that methylene chloridehaving a boiling point of 104 F. and gelatin melting at the sametemperature renders the two materials ideally suited for combined use inthis coating operation.

The formulation is then placed in fountain 28 and applied by a threeroll technique as previously described. Transducers 50 and 51, heaterelements 33 and 34 and solvent recovery hood 23 all cooperate to effectsubstantially complete solvent recovery.

Other water soluble polymers which can be used in place of or inconjunction with the bloom gelatin include the polyampholytes,polyvinylacetate, polyvinyl alcohol, polyvinylpyrrolidone, isopropylcellulose (Klusel-Hercules Powder Co.), methyl cellulose, casein glueand similar proteinaceous materials. In addition, the above materialscan also be mixed with light sensitized materials such as ammonium orpotassium dichromate, silver halide salts, and the like for formingphotographic images on the web substrate or forming oleophillic coatingswhen a light sensitizer is present.

EXAMPLE H1 The present example is an illustration of foam coating ofgasket materials which can be used for tin can covers, jar closures, andthe like. In this example, a web gasket material receives two separatecoatings applied in separate or continuous steps.

The first adhesive formulation is prepared from the followingingredients:

Parts by weight Diethylcyclohexylamine (amine catalyst) 50 Methylenechloride 50 The amine catalyst and methylene chloride are mixed andapplied by aerosol spray to the web substrate in accordance with thetechniques described in this application. A temperature of 70 F. at theregion of adhesive formulation deposit and a web speed of 500 to 2000feet per minute can be employed. Vaporization of the methylene chloridecan be facilitated by means of ultrasonic treatment of the coated webprior to the heating thereof.

A urethane adhesive composition for the second coat is then preparedfrom the following ingredients:

parts by weight of Vorite 101 caster based polyester prepolymer (BakerCastor Oil Co.)

10 parts by weight glycerine If desired, parts by weight of Asbestine(International Pulp Co.) may be added to each 100 parts of adhesive baseto increase the bonding of the foamed polymer to the substrate. Also,very finely ground glass fibers or boron fibers may be employed in thisconnection. An oleophillic lignin polymer filler (West Virginia Pulp &Paper Co.) can also be employed. The above formulation is then dispersedin 13 a chlorinated-fluorinated solvent such astrichlorotrifluoroethane.

The above urethane adhesive is then sprayed on the substrate containingthe amine catalyst. Ultraviolet irradiations of the urethane adhesivebefore application acts to improve the bonding properties of thecoating. Other coating and printing techniques can be used with themethod of this example to provide selective depositing of the coating ina predetermined design or pattern such as, in the forming of gasketrings on a metal or plastic web which ultimatelv is stamped into aclosure cap.

EXAMPLE IV Pts. by wt.

Molybdenum disulfide 10 Micro-size glass fibres (fiber glass) Teflonmicron size fibres 5 Hycar 1432 acrylic ester copolymer (B. F. Goodrich)Chlorothene NU (Dow Chemical C0., Midland,

Mich.) 70

These ingredients are combined in a fountain equipped with a dispersingmeans such as, for example, a Cowles Mixer. Ultrasonicgenerator-transducer units of the type identified by the referencenumeral 31 in the present application may be advantageously used inconjunction With a Cowles Mixer to insure uniform size reduction andthorough mixing. A refrigerated condensing unit is employed to maintainthe temperature in the fountain at 32 F. or below. These materials arethoroughly mixed together until all of the pigment particles have beenuniformly coated.

The formulation is applied directly to a paper, metal or plastic web byany of the techniques described in the present application and thensubjected to ultrasonic wave treatment and heat for solventvaporization.

If desired, the resinated or oleophillic coated pigment particles may bedried by heating the fountain to drive off the solvent. In this regard,a solvent recovery hood of the type described in this application can beadvatageously used to collect and condense the solvent vapors. Whendried the resinated pigment particles can be shipped or stored forsubsequent use.

The olephillic coatings obtained by this method are significantlyimproved over those produced by conventional fatty acid treatment sincethese coatings are polymerized and more permanent.

Generally, where a monomer is used in the formulation, a catalyst isnecessary to effect polymerization. Polymeric resins, such as theacrylic ester copolymer used in the above formulation, do not generallyrequire the presence of a catalyst for this purpose.

Other permanent type self-lubricants which may be used either alone orin combination with the molybdenum disulfide include Amoco 600 linearisobutylene polymer (Amoco Chemicals Co.), Microthene (U.S. IndustrialChemicals Co.), polyethylene sperical micron beads, micro glass beads,boron micron fibers, tungsten disulfide, molybdenum selenide, tungstenselenide, graphite Teflon micron size fluorocarbon powder, anthracene,micron size nylon polycaprolactum heat stabilized powder, tetraethyllead, di-n-butyltin sulfide and molybdenum xanthate.

14 EXAMPLE v Pts. by wt.

Silicone dimethylpolysiloxane polymer 20 Chlorothene NU (Dow ChemicalC0., Midland Mich.) 78

Tributyl tinlaurate (or other suitable catalyst) 2 The above ingredientsare thoroughly mixed together and applied to the web substrate at 32 F.This low temperature enables the coating to be uniformly applied inthicknesses of from monomolecular up to 2 mils thick. The thus depositedweb is then subjected to ultraviolet irradiation wherein the siliconepolymer in the presence of a catalyst is polymerized. Four ultravioletlight lamps spaced a distance of l to 8 inches from travelling web, eachbeing of 2200 to 2800 angstron units, are used with a Web speed of to3000 feet per minute.

After the ultraviolet irradiation, the coated web is subjected to highfrequency waves (25,000 cycles per second) to improve the bondingproperties of the silicone polymer and facilitate solvent release. Thesolvent is heated to 180 F. (boiling point of Chlorothene NU) and theevaporated solvent vapor collected and condensed in the solvent recoveryhood.

In this example, it is important to note that the silicone polymers areadvantageously applied to web substrates at low temperatures, 32 F. orbelow, since at these temperatures they have a low viscosity index whendispersed in chlorinated or fluorinated sol-vents. The techniquesdescribed in this example can also be used to provide combinedexpoxy-polyamicle resin coatings to webs and object surfaces.

EXAMPLE VI This example relates to a method of treating nonprintablesurfaces with a polymerizable coating formulation that acts as a goodreceptive surface for ink and coating deposits. Examples of thenon-printable surfaces which can be treated in accordance with thismethod are those composed of polyvinyl fluoride, polytrifluoroethylene,polytetrafluoroethylene, polyesters, polypropylene and polyethylene.

A typical coating formulation includes the following ingredients:

Pts. by wt. Tung oil fatty acid S Toluene sulfonic acid 5Trichloroethylene (chlorinated solvent) 80 Scrap acrylic resin (resinbonding vehicle) 10 The above ingredients are thoroughly mixed whilebeing maintained at a temperature of from F. to F. The formulation isthen applied to the web or object surface to be treated by the aerosolor foam coating method described in this application. Depositing of theaerosol or foam formulation at low temperatures (around 32 F.) isdesirable. Ethylene oxide or hexafluoroacetone is included in theaerosol or foam coating formulation.

The coated web is then subjected to corona discharge treatment whichpolymerizes the coating deposits and activates the polymer surface.

Ultraviolet irradiation can be used in conjunction with the coronadischarge treatment. Also, ultrasonic wave treatment of the coated Webcan be used in combination with these polymerization inducing techniquesto improve the coating.

Sulfur trioxide may be used either in place of, or in combination with,the toluene sulfonic acid or tung oil fatty acid. Also, if desired, apigment or coloring can be added to the formulation to provide a coloredcoating.

1 5 EXAMPLE v11 This example is particularly concerned with coating orprinting of paper, plastics and metalswith inks or coatings whichcontain high atomic numbered pigments which backscatter beta rays to adetection system containing low emitting radioisotopes. I

The following ingredients are used in preparing the ink or coatingformulation:

Pts. by wt. Zein (Corn Products Co.) resinous material 20 Methylenechloride (chlorinated or fluorinated solvent) 70 Bismuthoxychloride-BiOCl (High Z beta emitter,

high atomic numbered pigments) The above ingredients are thoroughlymixed together at 32 F. to 70 F. The preferred temperature fordepositing this formulation as a coating or ink onto the travelling webis between 32 F. and 70 F. After the coating or ink has been depositedon the web substrate, it is then subjected to ultrasonic sound andthermal heat to evaporate the solvent.

Other resinous polymer materials which can be employed include polyvinylalcohol, polyvinyl acetate, gelatin, thiolated gelatin, silicone esters,fumaric rosin and shellac.

Other high Z beta emitter pigments which can be employed include:bismuth oxychloride, lead tungstate, barium tungstate, litharge, thoriumoxide, iodoform, phosphotungstic acid type pigments, and cadmium sulfidepigments. ,7

A radioisotope which can be used in this process are those which emitlow energy not exceeding about 0.3 million electron volts and alphaemitters, such as polonium. Examples of such radioisotopes are hydrogen3, carbon 14, nickel 63 and polonium. The radioisotopes carbon 14, inthe form of barium carbonate, calcium 45 in the form of calciumchloride, sulfur 35 in form of barium or cadmium sulfide, promethium 147in the form of promethium chloride; all of which emit pure beta rays.These radioisotopes are produced in atomic piles or by means of acyclotron and may be purchased from the Atomic Energy Commission, OakRidge, Tenn.

EXAMPLE VIII This example concerns a method of providing glass bottlesand containers with a colorless, ultraviolet absorbent,abrasion-resistant, protective coating. According 1y, food productswhich are adversely efl ected by ultraviolet rays can be safely packagedin clear containers coated in accordance with this method so as to be infull view to the purchaser and without danger of deterioration caused bysunlight or other sources of actinic radiation. As such, this methodeliminates the need for amber and brown colored containers.

A typical colorless coating formulation includes the followingingredients:

'Pts. by wt.

Acrylic scrap resin 6 Tinopal S'FG (Geigy Dyestuff Co., New York)naphthotriazolystilbene derivative exhibiting ad vantageous UV absorbingproperties 2-4 Toluene sulfonic acid or glacial acetic acid 2+4 Ethylenedichloride 86 The provision of an ultrasonic generator and transducerunit in the formulation bath insures uniformity of the coatingformulation applied to the object surface.

The necessity for supplying external heat to vaporize the solventcomponent will be determined by the boiling point of the particularsolvent employed and the temperature of the bottles being coated.

The acrylic resin in the above formulation can be replaced by varioussilicone and other polymer resins.

In the above formulation, the acrylic resin furnishes the advantageousabrasion resistant qualities of the coated bottles. The toluene sulfonicacid or glacial acetic acid functions to bind the coating to the objectsurface.

EXAMPLE IX The present example is directed to the manufacture of novelelectro-luminescent panels. The coating techniques of the presentinvention employing the use of fluorinated and chlorinated solvents areparticularly useful in making these panels since these solvents aredielectric and nonpolar and, as such, do not interfere with or disturbthe electro-luminescent conductive properties of the coatings.

The panel consists of two members which are adhered together or joinedby any appropriate means I The first member is composed of an aluminumfoil on which an electro-luminescent coating is applied. This coating isprepared from the following ingredients:

Pts. by wt.

The second member is composed of a plastic film on which is applied apair of coatings. The first of these coatings is in the nature of apartially conductive primer layer while the second coating ischaracterized by more efl'icient electrically conductive properties.

-In selecting the web material to be used to form the second member, itshould be noted that since the light radiation in the finished panel isto be transmitted therethrough, the web should be of a transparent ortranslucent material. Typical examples of films which may be usedinclude cellulose acetate, Mylar" (E. I. du Pont) a polyester plasticfilm, polyvinyl fluoride, polyproxylene, polytetrafluoroethylene andpolytrifiuorochloroethylene.

In forming the second member, the following ingredients are used in atypical coating formulation for the primer layer:

Stannous tin chloride 10 Toluene sulfonic acid 10 An azeotropic mixturecomposed of 43% perchloraethylene and 57% Z-nitropropane Theseingredients are combined and thoroughly mixed together at a preferredtemperature of 70 F. The formulation is deposited as a coating on theweb at a preferred temperature of between 104 F. and 114 F. Offsetgravure or aerosol spray techniques are preferred for this step. Thesolvent component of the thus coated web is heated to F. (the boilingpoint of the azeotropic mixture). In this regard, if desired, ultrasonicwave treatment can be used to promote cavitation of the solvent andthereby facilitate the removal thereof. As before, the solvent vapor iscollected and condensed in a solvent recovery hood. 1

After being coated and dried, the plastic web is then coated with asecond formulation prepared from the following ingredients: A

These ingredients are combined and thoroughly mixed together at apreferred temperature of 104 F. and deposited on the web at a preferredtemperature range of between 32 F. and 104 F. The ultrasonic wavetreatment can, if desired, be used to facilitate solvent removal. Thesolvent component is heated to 104 F. and the solvent vapor is collectedand condensed by means of the solvent recovery hood.

Other resinous copolymers which may be substituted in place of Hycar202. are N-vinyl-Z-pyrrolidone, tung oil varnish, epoxy resins,polyamide resins, and nylon polyamide resins.

After each of the above coated members are formulated, they are joinedtogether in a sandwich construction by placing the luminescent coatingof the first member in intimate contact with the electrically conductivecoating of the second member. Connecting the foil backing or substrateof the first member and the primer layer of the second member to asuitable power supply will result in the activation of the luminescentcoating. Suitable means for keeping the respective panel members securedtogether in the sandwich construction include ultrasonic or heat sealingtechniques.

EXAMPLE X I Pts. by wt. Crude crystal violet carbinol 80 Unoxidizedhemotoxylin (logwood) 50 Methylene chloride 1000 Benzyl trimethylammonium hydroxide (36% aqueous solution) 10 The above ingredients arecombined and the mixture stirred with heat for one hour at the refluxtemperature. The residue is a light tan solution which, after filteringat about 75 C. and cooling, results in a white crystalline product whichhas a melting point of 100 C. This colorless product has thecharacteristic of producing a jet black stain with a strong violet tonewhen contacted with a tannic acid-metallic salt.

The specific coating formulation to be applied to the paper web includesthe following ingredients:

Pts. by wt. The crystal product produced by the present method 20 Theabove ingredients are combined and thoroughly mixed together and appliedto the paper web by aerosol spraying or .gra-vure methods. If desired,ultrasonic wave treatment can be used to cavitate the solvent component.After being subjected to the ultrasonic treatment, the methylenechloride is evaporated from the web by heating to 104 F. (the boilingpoint of this particular solvent).

Other crude coal tar colorless carbinols include 3,3,bis (Pdimethylaminophenyhfi dimethylamino phthalide crystal violet lactone;3,3,bis(P-dimethylaminophenyl phthalide malachite green lactone;3,7,bis(diethylamino)- 9- (-Carboxyphenyl)Xanthenerhodamine-B-N-phenylactam and 3,3,bis(P-dimethylaminophenol)4,5,6,7tetrachlorophthalide blue lactone.

Other materials which can be substituted for the logwood include BrazilWood (Hypernic), Persian Berries, Cochineal, fustic, gall, Quebracho andcatechols. Similar- Pts. by wt. Natural wood tannin 10 Ferrous ironsulfate 10 Bentonite clay or inorganic mineral clays 2/0 Methylenechloride 60 Raylig TA (sodium li'gnosulfonate, Rayonier, Inc.) 20

The above materials are thoroughly combined and applied to a paper webby means of any of the coating techniques described in this application.Polymerization of the coating by the ultraviolet radiation techniques ofthis ap plication may [be employed. Similarly, ultrasonic wave treatmentmay be used to facilitate solvent removal.

Tannin acid or pyro-gallic acid may be substituted in place of or usedin conjunction with the natural wood tannin in the above formulation.

EXAMPLE XI This example relates to aerosol foam coating of substrates.In particular, it concerns the use of collapsible foams which, whensubjected to ultrasonic Wave treatment collapse and coalesce intouniform film coatings.

.Bentonite colloidal clay, color pigments, dyestufls and inorganicfillers such as titanium dioxide and zinc oxide may be incorporated intothe aerosol foam to produce the desired color and opacity in thecoating.

Polymers, resins, starches and proteins may be incorporated into theaerosol foam coating for improved bonding and film formingcharacteristics.

The following ingredients are used in a typical coating formulation:

Pts. by wt. Polawax A 31 (Croda Co., N.Y., a mon-ionic emulsifying wax)3.5 Methylene chloride 51.9 Propylene glycol 6.0 Gentron 11 (AlliedChemical Co., trichloromonofluoromethane) 4.0 Distilled water v 33.6Polyvinyl pyrrolidone 10.0 Pigment or color component 10.0

It should be noted that there are a variety of polymeric resinousmaterials which may be substituted in place of or used in conjunctionwith the polymeric constituent identified above. These include, forexample, hydrolizable proteins, cellulosic polymers, starches and thelike.

The above ingredients are combined, mixed and pressurized for aerosolspraying. Any of the propellants described in this application may beused in place of the Gentron 11 or in conjunction therewith. In thisregard, it should be noted that these propellants also act ascosolvents.

After being applied to the web or object surface, the foamed coating issubjected to ultrasonic treatment causing the foam to collapse (degas)and coalesce to provide a uniform coating.

The coated web is then heated in order to vaporize the solventconstituent of the coating formulation. The vaporized solvent iscollected and condensed in the novel solvent recovery hood of thisinvention.

EXAMPLE XIII This example is directed to the forming of resinatedpigments in order to impart oleophillic properties thereto. In thisconnection, it should be noted that organic and inorganic color pigmentsand dyestufis when in a press cake form exhibit hydrophillic propertiesdue to the surface of these particles having an aqueous coating. Assuch, the particles tend to agglomerate and exhibit hydrophillicproperties which are generally undesirable for use in coating of web orobject surfaces.

A typical formulation includes the following ingredients: I

- Pts. by wt. Lithol red water press cake 20 Linseed oil 60 Methylenechloride p 20 The lithol red press cake is in an agglomerate form andusually containsfrom 20% to 30% water. This water concentration ischaracterized by aqueous coatings on .each of the pigment particles.Other organic. and inorganic pigments and coaltar dyestuffs which may besubstituted or used inconjunction with the lithol red include hansayellow, iron bue, phthalocyanine blue and green, chrome yellow,phosphotungstomolybdate toners, cornplex salts of cationic basic coaltar dyes, inorganic clays,

formulation are first thoroughly mixed together and cooled to 32 F. orbelow in a mixing apparatus equipped with a Cowles mixer blade. Thelithol red press cake is then added. Since the temperature of thesolvent and oil is below the freezing point of water, the aqueouscoatings on the pigment particles quickly freeze and separate from thepigment particles, enabling the linseed oil to be coated on therespective pigment particles. The Cowles mixer breaks up theagglomerates and insures uniform coating of the respective pigmentparticles.

If desired, CO or N may be bubbled through the bath in order to maintainthe same at the predetermined low temperature (32 F. or below). Also,uniform dispersion and disintegration of the pigment particles can beprovided for by the use of an ultrasonic transducer and generator unit,such as that described in the present application and identified by thereference numeral 31.

After the pigment particles have been coated with the linseed oil, heatis applied in order to vaporize the solvent and water. A solventrecovery hood of the type described in this application can beadvantageously used to collect and condense the solvent (methylenechloride). If desired, ultrasonic treatment at this step of theoperation can "be used to promote solvent cavitation and facilitatevaporization. The residue remaining is a resinated pigment particleproduct exhibiting advantageous oleophillic properties.

EXAMPLE XIII This example is directed to a collagen coating techniquewhich embodies the use of the heavy solvents and coating methodsreferred to in the present application.

The coating formulation is prepared from the following ingredients:

Pts. by wt.

Collagen 40 Citric acid 10 Water 40 Methylene chloride 100 The citricacid, water and methylene chloride are thoroughly combined andmaintained at the melting point of the collagen (around 105 E). To thismixture, the collagen is added with stirring until a gelatinous mass is'20 formed. The methylene chloride is then added with stirring-toprovide a'heterogenous mixtureiwhichis then uniformly applied to a websubstrate in'accordance' with the techniques described in the'presentapplication.

Under certain circumstances, it is desirable to-pretreat the collagenmass-solvent mixture withultrasonic dispersion means in order todepolymerize or fluidize the mass. In this regard, it should also benoted that aCowles mixer can be advantageously used to insureuniformityof the coating formulation. 7

Other acids which maye be substituted or used in con junction with thecitric acid include lactic, tartaric and various solid-type acidmaterials.

. While this example has been particularly concerned with-the applyingof the collagen formulation as a coating on a web substrate by gravure,aerosol and like techniques, it should be noted that this formulationcan be extruded, molded, cast or preformed-,etc, to provide a film-likeproduct. 1 v e While in the foregoing specification, detailedexplanations of the variousembodiments of the present invention havebeen set forth for the purpose of explanation, many variations may bemade by those skilled in the art without departing from the spirit andscope of this invention as set forth in the appended claims.

,I claim: I v a 11 The method of coating a web surface with a coatingformulation which includes a chlorinated solvent, com,- prising thesteps of depositing said coating formulation on the Web surface,

treating said coated web with high frequency sound waves for promotingsolvent release of said coating formulation from said. coated websurface, heating the chlorinated solvent component of said coatingformulation to its boiling point to promote vaporization of saidchlorinated solvent, and

collecting and condensing said vaporized chlorinated solvent vapors.

2. The method of claim 1 wherein said formulation is deposited on suchWeb surface at a temperature no higher than F.

3. The method of claim 1 wherein said formulation is deposited on saidweb at a temperature no higher than 32 F.

4. The method of claim 1 wherein said coating formulation includes achlorinatcd-fluorinated solvent.

5. The method of claim 1 wherein said high frequency sound wavesarebetween 20,000 and 30,000 cycles per second.- I

Long 204-1574 S ALFRED L. LEAVITT, Primary Examiner J. H. NREWSOME,Assistant Examiner us. c1 X.R. 117-911 R; 204-158 s

